DE3232614A1 - DRY MIXTURES FOR THE PRODUCTION OF AQUEOUS ADHESIVES AND THE USE THEREOF FOR GLUING PAPERS - Google Patents

Abstract

1. Dry mixtures for the preparation of aqueous adhesives or pastes based on water-soluble, nonionic cellulose ethers, characterized by a content of cold-water-soluble non-gelatinized starch ethers containing carboxymethyl and/or propyl sulfonate groups which have a degree of substitution in regard to the carboxymethyl groups of from 0.1 to 0.6 and in regard to the propyl sulfonate groups of from 0.1 to 0.5 and which are present in a quantity of from 20 to 95 % by weight, based on the mixture of starch ethers and cellulose ethers.

Description

32326U

^ HENKEL KGaA

Henkelstrasse 67 ZR-FE / Patents

4000 Düsseldorf, August 31, 1982 Dr SchOe / Ge

Patent application D 6552

"Dry mixtures for the production of aqueous adhesives and their use for bonding papers"

The invention relates to dry mixtures for the production of aqueous adhesives or pastes based on water-soluble nonionic cellulose ethers and water-soluble starch ethers containing anionic groups and their use for gluing papers or other absorbent cellulose materials.

Powder for the production of aqueous adhesive preparations based on cellulose or starch derivatives, which are used, inter alia, for gluing paper, in particular wallpaper, are known. However, are these adhesive preparations or pastes are often unsatisfactory in terms of their productivity and adhesive strength. Also, the processing properties of the powders are in many cases not such that they meet the increased requirements. Occasionally the dispersibility can leave something to be desired. The final viscosity the dispersion is possibly only achieved after half an hour to a full hour.

The delayed solubility often has the consequence that the swollen particles separate and one that is to be prepared Has to stir the paste often. Furthermore, the solubility can be dependent on the hardness of the water

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be a disadvantage. A high water hardness increases the solubility of many starch ethers adversely affected.

The object of the present invention was therefore to eliminate the disadvantages outlined and such Produce mixtures containing starch ethers, which are as independent as possible of the water hardness and temperature of the water. It should also be achieved that the pastes are improved in terms of their adhesive strength. or that less starch ether has to be used as a result of increased bond strength in order to obtain a satisfactory To achieve bonding of the papers or other substrates to be bonded.

According to the invention, this object is achieved by dry mixtures for the production of aqueous adhesives or Paste based on water-soluble, non-ionic cellulose ethers, characterized by a content of non-gelatinized starch ethers containing cold water-soluble carboxymethyl and / or propoxysulfonate groups, which have a degree of substitution with regard to the carboxymethyl groups between 0.1 and 0.6 and the propylsulfonate group between 0.1 to 0.5, and in an amount of 20 to 95 percent by weight, based on the mixture of starch ethers and cellulose ethers are present. The grain structure of the starch ethers used should be be completely preserved. You should be using organic water-miscible or partially water-miscible liquids, in particular monovalent alcohols with 1 to 5 carbon atoms.

Mixtures of these liquids can of course also be used as the reaction medium in the reaction will.

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However, the most favorable results are achieved when the alcohols mentioned are predominantly used. Of course it is also possible, in addition to the alkali required for the etherification, which is preferably in the form of grains of about 0.1 to 0.7, in particular 0.2 to 0.4 mm, is used, other common auxiliaries to be used in the reaction. In some cases, the known slight transverse Crosslinking with bifunctional halohydrins such as the bis-glycerol chlorohydrin-polyethylene glycol ethers or and epichlorohydrin itself ultimately have a beneficial effect on the structure of the aqueous adhesive solutions.

Practically all of them are used as starting material for the production of the starch ethers to be used according to the invention common starches in question, i.e. corn starch, potato starch, tapioca starch and rice starch. the end For practical reasons, the invention is explained experimentally using native potato starch. Depending on the desired external conditions can be the starch as a commercial product with the natural water content or can also be used pre-dried. The carboxymethyl and / or the oxypropylsulfonate radical are introduced in a manner known per se, the solid state of aggregation during the entire reaction time should be preserved (see DE-PS 864 396). The residues mentioned can be introduced simultaneously or in succession.

Due to the acidic properties of the sulfonic acid group or the carboxymethyl radical, the inventive Starch ethers are used in the form of their water-soluble salts. For practical reasons, this is Sodium salt preferred, although other water-

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soluble salts such as potassium or ammonium salts can be used.

The starch ethers prepared according to the above manner show particularly favorable behavior with regard to this the explosiveness according to VDI guideline 3673 ("Geigy dust test"), so that the "StO" level is practically always achieved.

The non-ionic cellulose ethers contained in the dry mixes are, for example, methyl cellulose, Hydroxyethyl cellulose, hydroxyethyl hydroxypropyl cellulose, methyl hydroxypropyl cellulose. Is preferred Methyl cellulose used itself or a cellulose ether which predominantly contains methoxyl groups.

The mixing ratio between starch ethers and cellulose ethers can be varied within wide limits. However, such dry mixtures are preferred in which the Content of those in the grain structure substituted with carboxymethyl or propylsulfonate groups Starch ethers between 40 and 85 percent by weight, based on the dry mixture.

The mixtures are distinguished by particularly favorable application properties. You let yourself particularly easy to bring into solution even in hard water by simply stirring. Your solutions show related the viscosity synergistic values. This is shown in FIG. 1 in curves A to D and could can by no means be foreseen. Were starch ethers instead of the starch ethers produced using the special process? used, in which the carboxymethyl groups via a wet or dry process with at least partial flow the grain structure were introduced, showed the

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Viscosity curves showed a linear course or were even more unfavorable (negative synergism).

A preferred field of application of the dry mixtures according to the invention is their use for the production of aqueous adhesives or pastes for gluing paper or other absorbent cellulose materials, in particular wallpaper, on a wide variety of possibly less absorbent or prepared surfaces. These preparations are often made to make it easier to remove wallpaper later.

To produce the aqueous adhesives or pastes from cellulose ethers and starch ethers, these can be used directly be stirred into the water. As is often the case, you can add further additives beforehand, to improve certain properties. By using redispersible synthetic resin powder such as Polyvinyl acetate, water resistance can be improved. It is also possible to use preservatives and to use additives that prevent the mixtures from caking.

The approach ratio of the dry mixture with water can be varied within certain limits, whereby the final viscosity of the adhesive solution or the paste and the adhesive strength can be influenced indirectly. In general, one becomes a ratio of Mixture of starch ether and cellulose ether to water between 1:25 and 1:80, in particular 1:30 to Select 1: 65.

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In the examples below, the adhesive solutions or paste obtained were - unless stated otherwise - made up with water at 15 ° dH. The viscosity was measured at 20 ⁰ C according to Brookfield (RVT, 20 rpm, spindle 4).

The test of the dry adhesive strength was carried out on three-layer beech plywood (8 × 5 × 0.45 cm). For this purpose, the test specimens were marked 3 cm from the narrow side parallel to the narrow side, so that when a test area of 15 cm revealed. The paste was applied on one side with a 200 Λα spiral doctor blade. Was fixed with four brackets, a total of about 40-50 N was exerted on the test surface. After 24 hours the Test specimen with the tearing machine at a test speed torn at 50 mm / min. For each adhesive 5 test specimens were glued and measured.

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example 1

A starch ether (CMS) was produced, with one to 20.8 kg of potato starch (19% Η, Ο) in 8.0 1 90% isopropanol after alkalizing with 1.1 kg NaOH prills (0.2-0.3 mm diameter) with stirring, 2.8 kg sodium salt the monochloroacetic acid was allowed to act at 60-70 C. After a reaction time of 3 hours, the reaction product was freed from the solvent in vacuo.

This starch ether was free-flowing and the grain structure was retained. Although it was a powdery product, the behavior in the "Geigy dust test" according to VDI guideline 3673 with regard to the dust explosion ^{capability resulted in a classification in class 11} StO ". This carbojymethyl starch had a DS of 0.22.

Mixtures with methyl cellulose (DS 1.8) were made with the dry starch ether and these were im Ratio 1: 60 stirred into water. After the solution had stood for 1 hour, there was a dependence on Viscosity (20 ° C., Brookfield), as shown in FIG. 1, curve A. It is the curve of the curve (ordinate mPa-s against The abscissa is 0 to 100 percent by weight of methyl cellulose).

The strength values with a content of 20%, 40%, 60%, 80% MC are 73; 88; 92; 85 N / cm ² .

Example 2

18 kg of potato starch (10% H ₂ O) were mixed with 2.8 kg of the sodium salt of monochloroacetic acid in a turbulent mixer and with a solution of 4.0 kg of methanol

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(99%) and 12.5 g of a bis-glycerol chlorohydrin polyglycol ether (molar weight 780). The alkalization was carried out by adding 1.16 kg of NaOH in the form of prills (0.2-0.3 mm diameter). The mixture was left to react ^{at 65 to 70 °} C. for 2 hours with gentle mixing. A methanol / water mixture was then drawn off with evacuation.

The grain structure was completely preserved.

Explosion behavior "StO"

Degree of substitution 0.23

Residual moisture 8% (110 ⁰ C in the drying cabinet

up to constant weight)

Mixing with methyl cellulose gave curve B in FIG. 1.

Strength: 40% 60% 80% MC 63 72 81 N / cm ² .

Example 3

20 kg of potato starch (19% H ₂ O) were sprayed with 1.17 kg of the sodium salt of monochloroacetic acid in a turbulent mixer with 3.0 kg of i-butanol and after addition of 0.65 NaOH in the form of prills (0.2-0 , 3) sprayed with 5.55 kg of a 60% aqueous epoxypropanesulfonate (Na-Salz) (French. Patent 1,369,825) and 3.0 kg of i-butanol for the purpose of alkalization. The reaction takes place in the mixer at 45-70 ⁰ C for 3 hours. The reaction temperature was increased slowly. After 1 hour, the solvent / water mixture was drawn off with gentle evacuation.

Degree of substitution: carboxymethyl groups 0.1

Oxypropanesulfonate groups 0.3 Explosion behavior "StO"

Residual moisture: 8% ( ^{volatile constituents at 110 °} C.) Mixtures with methyl cellulose gave curve C in the figure. Average shear strength on beech wood 72 N / cm at 60% on methyl cellulose.

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Example 4

19 kg of potato starch (19% H ₂ O) were sprayed with 2.9 kg of the sodium salt of monochloroacetic acid in a turbulent mixer with 4.0 kg of ethanol (96%) containing 35 g of bis-L-glycidylchlorohydrin polyglycol ether (MW 780). Then, 1.2 kg of sodium hydroxide were added in the form of prills (0.2-0.3 mm 0) with slow mixing, and then 2.9 kg of propylene oxide were added uniformly over 4 hours at 45-50 ⁰ C.

The temperature was then slowly increased to 70 ^° C. within 1.5 hours. After a further 1/2 hour, the ethanol / water was stripped off with suction. Residual moisture: 8% (volatile components at 110 ^° C.) Completely preserved grain structure, explosion behavior "StO".

Degree of substitution of carboxymethyl groups 0.22 Oxypropyl group content 0.5 per mole of anhydroglucose unit.

Mixtures with methyl cellulose gave curve D in FIG. 1. Average shear strength on beech wood:

76 N / cm ² .

Example 5 _t

Commercially available 19 kg of corn starch (13% H ₂ O) were mixed with 2.8 kg of the sodium salt of monochloroacetic acid in a turbulent mixer and sprayed with 1.1 kg of NaOH in 8.0 90% i-propanol. The reaction with moderate stirring was completed in about 2 hours at 60-70 ⁰ C. After standing for 3 hours, the mixture of i-propanol / water was then drawn off with evacuation until the residual moisture content was 7.5% (110 ^° C. in a drying cabinet).

The grain structure was completely preserved, the explosion behavior "StO".

A dry mixture of 60% of the carboxymethyl starch and methyl cellulose produced in this way resulted in

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a make-up ratio of a) 1: 35 or b) 1: 60 with water on beech wood bonds of average shear strength;
a) 55 N / cm ² b) 45 N / cm ² .

Example 6

The starch mixed ether according to Example 3 was made up in a ratio of 3: 7 with hydroxyethyl cellulose (HEC, 44% hydroxyethyl content) in water 1:60. After a swelling time of 1 hour, a viscosity of about 3,600 mPas was found. The calculated value was around 3,100 mPa.s. Average shear strength on beech wood 62 N / cm ² at 60% mixed ether according to Example 3.

Example 7

The starch mixed ether according to Example 3 was in the ratio 3: 7 with methylhydroxypropyl cellulose (MHPC, 21% methyl groups, 38% hydroxypropyl groups) in water Estimated 1:60. After a swelling time of 1 hour, a viscosity of about 2,350 mPa · s was found. The calculated. The value was approx. 2,150 mPa · s.

Average shear strength on beech wood 65 N / cm ² .

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Comparative experiments

A) After 18 kg of potato starch (19% H ₃ O) had been suspended in 25 kg of water and a pH of 11 had been set with sodium hydroxide solution, 4.5 g of epichlorohydrin were allowed to flow in with stirring and the mixture was left to stand at 30 ^° C. for 16 hours. Then 3.3 kg of the sodium salt of monochloroacetic acid were added to the starch suspension. The suspension was mixed with 2.5 kg of 50% sodium hydroxide solution by means of a metering pump in such a way that there were always proportional volumes of suspension and sodium hydroxide solution. The reaction mixture was pumped through a steam-heated static mixer, with a residence time in the heating zone of 30 seconds. The product temperature at the outlet was 95 ^° C. The highly viscous reaction mixture was dried on a drum dryer and the carboxymethyl starch was ground. The grain structure of the starch grain could no longer be recognized.

For comparison, mixtures of this carboxymethyl starch and methyl cellulose were produced. The found Visibility values are entered in FIG. 2 and marked with V_.

B) A commercially available carboxymethyl cellulose produced by a dry process and having a degree of substitution of 0.7 was mixed with methyl cellulose. The viscosity values found are marked _{with V 11 in FIG.}

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Claims (5)

32326U patent application D 6552 V * HENKELKGaA ZR-FE / patent claims 1. Dry mixes for the production of aqueous adhesives or paste based on water-soluble, non-ionic cellulose ethers, characterized by a content of cold-water-soluble, carboxymethyl and / or propylsulphonate groups containing ungelatinized Starch ethers which have a degree of substitution with respect to the carboxymethyl groups between 0.1 to 0.6 and the propyl sulfonate groups between 0.1 and 0.5, and in an amount of 20 to 95 percent by weight, based on the mixture of starch ethers and cellulose ethers, are present. 2. Dry mix according to claim 1, characterized by a content of starch ethers, the grain structure of which is completely preserved and which are made using organic, water-miscible or partially water-miscible, monovalent alcohols with 1 to 5 Carbon atoms were produced. 3. Dry mix according to claim 1, characterized by a content of methyl cellulose and / or hydroxyethyl cellulose and / or hydroxyethyl hydroxypropyl cellulose and / or methyl hydroxypropyl cellulose as water-soluble, non-ionic cellulose ethers. 4. Use of the dry mix according to one of the claims 1 to 3 for the production of aqueous adhesives or pastes for bonding papers or others absorbent cellulose materials, in particular wallpaper. Sd 230 / 4'lHM'J i OI Ul 32326U I. Paluntanmulduiig D 6552 W HENKELKGaA ZR-FE / patents 5. Use of dry mixes according to claim 4, wherein the content is obtained in the grain structure starch ethers between 40 and 85 substituted with carboxymethyl or propylsulfonate groups Percentage by weight, based on the dry mixture. Sd230 / 438539 3.01.61